Longstaff, 21, fits Solskjaer's profile of young British players he can develop, much like Wan-Bissaka and James, and would likely command a fee of around £25m.
Wan-Bissaka travelled up to Manchester this week to complete a medical and finalise personal terms.
The Wales worldwide, also 21, enjoyed his breakthrough season in the 2018-19 Premier League campaign, scoring seven goals and registering five assists.
"I can remember watching the session and thinking afterwards, 'He did all right at right-back, '" said Kevin Keen, who was Palace's first-team coach at the time.
Wan Bissaka boasts of some of the best defensive statistics in the league and even in Europe, and is viewed as a welcome addition to a floundering Manchester United backline. "He has earned this opportunity & I wish him all the luck in the world on this new journey". That is something I want to be a part of.
Durant to engage four teams in talks
Worst case, if he's Carmelo Anthony now and goes to NY maybe he can't lead them to a championship and the PRESSURE would be on. In fact, they could be a serious championship contender for the next few years if everything goes right for them.
Paul Pogba could also depart after expressing an interest in leaving Old Trafford.
"It's an unbelievable feeling and an honour to call myself a Manchester United player and something I know that only a small number of players have the privilege to say", Wan-Bissaka told the club's official website.
Right-back Wan-Bissaka will be the sixth most expensive signing of the post-Ferguson era and here we look at how the five men who cost more have fared.
The 33-year-old has become a symbol of everything United fans have come to hate about the club and the decision to give him a new contract in February was met with a serious backlash.